No approved treatment existed for Sanfilippo syndrome — until Fayuvi cleared US regulators

The US Food and Drug Administration has cleared Ultragenyx's rebisufligene etisparvovec (Fayuvi) for children with mucopolysaccharidosis type IIIA — Sanfilippo syndrome type A, a rare inherited disorder that progressively damages the brain. It is the first FDA-approved option of any kind for the disease, and it arrives as a gene therapy: a one-time treatment designed to supply the missing cellular machinery rather than merely manage decline. For parents who have lived with the phrase 'there is no treatment,' the approval marks the moment a medical record of hopelessness gets its first hopeful entry.